Going from manual to TH400 transmission in my 69 C20

[Jake831]

I'm hoping for some help. I inherited a 69 C20 when my dad passed away. It's not a show truck, it's a good ole work truck that has a boom lift and the original engine from my 66 Chevelle.....two of the main reasons I kept the truck. Wanting to make it easier for my wife to drive I thought I'd swap out the 4 speed with a TH400. I bought another 69 C20 as a donor, thinking I'd have everything I'd need. Well, that serves me right for thinking!!

The donor had a 292 and mine has a 327. The kick down bracket and solenoid on the 292 will not work on the 327. I went junk yard shopping this weekend (where I ran into a guy with a beautiful 68 truck that turned me on to this website!) and found a few solenoids that are hooked to the 4bbl carbs, but my truck has a 2bbl. Does anyone know what the bracket and solenoid for a Small Block with a 2bbl carb looks like...better yet, where to get them?

If anyone has attempted to do what I'm doing and would care to share anything else I'm going to discover I'll need, I'd appreciate it. I was out cleaning up all the parts from the donor yesterday and crawled under my truck and I see the transmission cross bracket for the 4 speed is nowhere's close to the one for the TH400. Also noticed the drive line from my truck is much more stout than the one the came out of the donor, plus the middle bracket it totally different. Guess I'll be having a customer drive line made.

Thank you!
- Jake

[Mike C]

You are just running into a lot of the differences that exist with these trucks. Driveline length and the center carrier bearing have several variations. As you have observed, the crossmembers are different for the manual to the auto and the engines are mounted in different locations 6 to 8 as well.

Good luck with your project, eventually you will figure all the differences out and get it going. LOL>

[MARKDTN]

The kickdown on a TH400 is electric. I would look for a kickdown bracket that goes on the gas pedal rather than the carb. The later ones used that. Much easier to find. Not sure if a 73 up would work, but might? The automatic crossmember you will have to locate, but no big deal. Driveline might work from your donor if you get lucky or you may have to have 1 of the shafts redone at a driveline shop to get the right length. You will need the automatic column, shift linkage and brackets, cooler line, radiator with cooler provisions from your donor. You will have to move the big purple wires from the clutch safety switch to the column neutral safety switch. You will need a flexplate for the 327 and appropriate bolts.

[Jake831]

After pulling the TH400 I figured I'd be kicking myself if I didn't have it rebuilt. I picked it up yesterday and had a long chat with the guy. He told me several of the same things flex plate, bolts etc. Talked to him about the drive line issue how the donor one bolted up differently from my existing and how I'd most likely have to get one custom made. Turns out he can do the drive line work as well. He's been doing transmission work for over 50 years. He came highly recommended when I asked around. He works out of his house, and has a shop to die for! He doesn't do any of the pulling or installing, just rebuilding...at 74 yrs old, can you blame him? He also gave me a suggestion on the kick down issue and how I could easily wire in my own switch. He then told me if I got into a bind and needed help he could come take a look. This guy was a great find. I learned everything I know on knuckle busting automotive mechanic work from my dad and a close family friend (JD) who was a mechanic. JD passed away about 4 months prior to my dad, so I no longer have those go to guys for automotive stuff. Taking on this project I'm sure will test my abilities, but between this awesome website and the transmission guy, I'm sure I'll get it done!! I'm sure it won't be as quickly as JD and dad would have taken!!